TI­TAN XD LOW FUEL PRES­SURE

Diesel Power - - Top Tech Questions - Monte Wilkes via email

QUES­TION: I have a ’16 Nis­san Ti­tan XD diesel with 36,900 miles on it. I do a lot of tow­ing, and on a few oc­ca­sions (when the fuel-range in­di­ca­tor drops be­low 65 miles re­main­ing), a “Low Fuel Pres­sure” warn­ing dis­plays. Noth­ing changes in drive­abil­ity, but the first time it hap­pened it def­i­nitely caught my at­ten­tion. After fill­ing up, the warn­ing goes away, and it doesn’t ap­pear again un­til the driv­ing range hits that 60- to 65-mile mark. Is there a prob­lem with the fuel sys­tem or the tank? I fol­low the owner’s man­ual for all the main­te­nance. With only a 26-gal­lon tank and 10 mpg when tow­ing, this is be­com­ing a range is­sue for me. AN­SWER: The CP4 in­jec­tion pumps on new diesel en­gines are very finicky about be­ing starved of fuel. They’re prone to fail­ure in low-fuel con­di­tions, and this is costly be­cause cor­rect­ing the dam­age usu­ally re­quires re­plac­ing the en­tire fuel sys­tem. The “Low Fuel Pres­sure” and “Low Fuel” warn­ings are Cum­mins’ way of en­sur­ing the driver is very aware the fuel level is near­ing a point of con­cern and that he or she has ad­e­quate time to re­fuel—much like diesel-ex­haust-fluid warn­ings. When the fuel level gets be­low a quar­ter tank, the ECM trig­gers those warn­ings. It will also send the same alert when there’s a fuel-pres­sure drop due to de­bris get­ting into the pick-up in the tank or if there’s re­stric­tion far­ther up­stream in the two fil­ters in the low-pres­sure side of the fuel sys­tem. If the “Low Fuel Pres­sure” warn­ing comes on be­fore a quar­ter of a tank, there could be a pres­sure-sen­sor is­sue, con­tam­i­nated fuel, bad fuel- fil­ter O-ring, clogged fuel fil­ters, a fil­ter that has a failed check valve, a lift pump dy­ing, or low volt­age to the fuel pump. These are all items a deal­er­ship ser­vice depart­ment should check while the truck is still un­der war­ranty. If you want to ex­tend the driv­ing range of the stock fuel tank, you might con­sider in­stalling a Sin­is­ter Diesel fuel-tank sump, which draws from the bot­tom of the tank. A bet­ter choice is to re­place the stock mid-ship fuel tank with a high-ca­pac­ity ver­sion such as the 50-gal­lon of­fer­ings from Trans­fer Flow or Ti­tan Fuel Tanks. Ei­ther one will nearly dou­ble your cur­rent driv­ing range.

Nis­san Ti­tan XD diesels will warn the driver the fuel level is low when the miles-to-empty in­di­ca­tor reads 60 to 65 miles, usu­ally trig­ger­ing a “Low Fuel Pres­sure” warn­ing that will hope­fully as­sist the driver in not run­ning out of fuel (which can dam­age the CP4 in­jec­tion pump and fuel sys­tem).

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